During the debate over whether to invade Iraq, or whether to stay in Afghanistan, many people looked back to World War II, describing it as a good and just war — a war the U.S. knew it had to fight. In reality, it wasn't that simple. When Britain and France went to war with Germany in 1939, Americans were divided about offering military aid, and the debate over the U.S. joining the war was even more heated. It wasn't until two years later, when the Japanese bombed Pearl Harbor and Germany declared war against the U.S., that Americans officially entered the conflict.

But from 1939 through 1941, Americans were deeply divided between interventionism and isolationism.

"It's so easy, again, to look back and say, 'Well, all the things that the isolationists said were wrong,' " author Lynne Olson tells Fresh Air's Terry Gross. " ... But back then, you know, in '39, '40 and most of '41, people didn't know that. People had no idea what was going to happen."

Olson's book, Those Angry Days, shines the spotlight on the national debate over whether to go to war in Europe. President Franklin Roosevelt led the interventionist charge, while aviator Charles Lindbergh became an unofficial leader of the isolationist movement.

Because of Lindbergh's fervent isolationism, history has sometimes remembered him as a Nazi sympathizer, but Olson says that accusation is not quite accurate.

"He certainly was a racist in the sense that he thought people of northern European descent — i.e., whites — were inherently superior in every possible way to people who were not white, and the Germans obviously shared that view," Olson says.

Still, when the U.S. entered the war, Lindbergh wanted to fly for his country. Roosevelt wouldn't allow it, but Lindbergh's friends arranged for him to serve as a civilian consultant testing planes in the South Pacific.

"Charles Lindbergh was never happier than in a cockpit," Olson says. " ... He didn't really like politics at all, but [the cockpit] was his place."

Interview Highlights

On the question of Lindbergh's Nazi sympathies

"He admired the Germans' technological expertise. Bottom line: Charles Lindbergh was a technocrat. That's what he was really interested in, and the Germans were experts in technology. And he also admired what the Germans had done in terms of reviving country, and he certainly was sympathetic with Germany. Often he would say, 'You know, I don't approve of what they're doing to the Jews. I don't approve of their denial of freedoms,' but you never really got the sense that he felt very strongly about that."

On Americans not feeling connected to World War IIEurope

"They looked on it kind of like a movie. ... It was something that just didn't affect them. We didn't have the technology. We didn't have the instant communication. We didn't have the ability to travel — the ability to travel quickly — to Europe that we have now. And so most Americans — not all, but most Americans, especially those who lived in the heartland — really didn't feel that they had anything in common with Europe. They hadn't been there. They thought this was a distant place that they really had nothing to do with, and they felt that way until 1940."

On the Selective Training and Service Act of 1940, the first peacetime conscription in U.S. history

"The conscription bill was one of the most unpopular pieces of legislation, at least in the beginning, because we only had had a draft twice in our history before: the Civil War and World War I. The idea of a standing army was anathema to most Americans, as it had been to the Founding Fathers. We just didn't do that. I mean, that was not in the American scheme of things, and a group of private citizens said that we needed — in order to be a well-prepared country, in case we had to get into this war or even to defend ourselves — ... a standing army. We needed a draft. We needed to draft a million young men to be prepared in case this war ever touched our shores."

On why many students opposed U.S. intervention in World War II

"Students felt strongly because they were going to be the ones, you know, on the front lines if we got into the war, and they felt incredibly strongly that the first world war hadn't worked and that all these young Americans had been killed, and they didn't want to be next. You know, when I was doing research on the book, that whole subject reminded me a lot of Vietnam in the '60s. There was a very big anti-war student movement before World War II. And we think of World War II as a good war, but, you know, that's in hindsight. It turned out in many ways it was a necessary war for us, but that wasn't clear back then and certainly not to a lot of Americans. And so these kids were basically saying, 'Hell no, we don't want to go to war. This is something we absolutely do not want to do.' And this major isolationist organization ... America First was founded by a bunch of Yale students — Yale law students and Yale undergraduates — and among them were young men who went on to have incredibly illustrious careers. ... Gerald Ford was a Yale law student, and he was one of the founders of America First. Potter Stewart, who later went on the Supreme Court, was also a founder. Sargent Shriver, the first head of the Peace Corps, was a founder, as was Kingman Brewster, who later became president of Yale and, quite ironically, U.S. ambassador to Great Britain. Among the students who supported America First were John F. Kennedy, who was a Harvard senior, and Kurt Vonnegut and a young prep school student named Gore Vidal."